Sterilizer



SePty14, 1937 c. R. MEITZLER 1 2,093,334

STERILIZER Filed April 13, 1935 2 Sheets-Sheet 1 Y Q9 f is ATTORNEY SePt- 14,1937 c.R. MEITAZLER l 2,093,334

STERILIZR Filed April 13, 1935 2 Sheets-Sheet 2 Patented Sept. 14, 1937 UNITED sTATl-:s

PATENT OFFICE 093,334 sfrERILIzEn` Charles R. Meitzler, Rochester, N. Y., assigner oi one-half to Oscark I-I. Pieperv and one-half to Alphonse F. Pieper, Rochester, N. Y.

Appiiauon April'laisss, semi No; 16,120'

13 Claims.

This invention relates tok sterilizers and more particularly to sterilizers adapted to sterilize surgical Tinstruments or other medical equipment or supplies. y

An object of the invention is tov provide an improved and'efllcient sterilizer in which the heat is applied to the articles to be sterilized through the medium of heated' air or other gas,'r`ather than through a heated liquid.

Another object of the invention is the provision of such a sterilizer having adequate protection against contamination of the sterilized articles both during the sterilizing period and during the subsequent cooling period.

Still another object is the provision of such a sterilizer of simple and compact form, easy and relatively inexpensive to manufacture, and sturdy and simple in operation.

To these and other ends the invention resides in 20:V4 certain improvements and combinations of parts, all as will be hereinafter more fully described, the novel features beingpolnted out in the claims at the end of the specification.

In the drawings: y

Fig. 1 isa vertical section taken substantially centrally through sterilizing apparatusV constructed in accordance with a preferred embodiment of the invention, illustrating the parts in sterilizing position;

30 Fig. 2 isa similar view illustrating the parts in cooling position;

Fig; 3 is a horizontal section through one end of the apparatus, with the parts inV sterilizing position;

su)4 Fig. 4 is a similar view with the parts in cooling position; and

Fig. 5 is a diagrammatic view illustrating one suitable circuit arrangement.

The' same reference numerals throughout the 40 several views indicate the same parts.

The apparatus of the present invention includes a suitable sterilizing chamber formed by walls I I having an extension I2 at one end, and a removable closure I3 for closing a suitable opening 45- through which the articles to be sterilized may be inserted in and removed from the chamber I4v defined by the walls II. The chamber I4 may conveniently be of approximately rectangular shape with its top open and with the closure I3 50 removably associated with this top so as to clos'e it Pcompletely andv se'al the chamberl when the cover is in normal closed position. Suitable thermal insulation' I5 is preferably associated with the cover I3 to reduce transmission of heat The wall portions II and I2 are preferably of sheet metal. On the outer endof the extension I2 is' suitable thermal insulation I8, and beyond this insulation is a metal plate I9 having an annularshoulder v Mounted on the outer side of the plate I9 is an electric motor 25 having its shaft extended through the members I2 and I9l and the interposedv thermal insulation I8 and carrying a fan 25 within the extension chamber formedl by the member I2. A tight bearing is formed' between the motor shaft and the partition `members I2, I8, `and I9 through' whichy it extends, so that, although the shaft is free to rotate, no air or other ,gas can pass into ,or out of the sterilizing chamber through the shaft` opening, and the sterilizing chamber remains completely sealed against ingress of air when the cover I3 is in normal closed position. l i

kWithin'the extension I2 is a holder 30 in which is placed one or' more electrical heating elements indicated diagrai'nmaticallyl at 3|., The holder 30 do'es'notextend quite to the top of the extension chamber I2, but leaves a space between the top of the*Y holder and the'top of the extension chamv25 ber through which air may return when the fan 26'isin operation. It will be noted that the fan is'in alinement with and behind the heating elements 3I so as toblow air forwardly through these heating elements in the direction of the arrows in Figrl.

Walls 35 outside of and spaced from the walls II provide a chamber, passageway, or duct 36' extending" around the bottomysides and one end ofl thesterilizing chamberr I4. Still other walls 31`outside of and spaced from the walls 35 provide an Yinsulating compartment 33 extending around' the bottom,- sides, and one end of the walls 35, andsuitable thermal insulation is placed within the space 38k'. A' conduit 39 connects the cooling duct r36rv to the outside atmosphere at the endlof the apparatus remote from the motor 25 andfheat'ing elements3'l, the cuter end of this conduit 39 being"preferablyccvered by any suitable screen 40. 4D

Around the motor 25 and some distanceoutwardly therefrom isa housing member 45 form;- ing, in effect, an extension of the cooling passageway 36, ardhaving'a large opening at' its outer end and a guiding'ilange I6 extending inwardly from the opening.; Ausleevel'l is suitably lmount-- ed inthe flange for axial movement therealong, thefinne'rmostwpc'sition of the sleeve 4l being deterr'nined by contact of the inner end ofthe sleeve shoulder 20, as shown in Fig. 1, and the outermost position of the sleeve 4T being determined by a suitable stop such as the screw 48 which comes into contact with the inner edge of the guiding flange 136, as shown in Fig. 2. The outer end of the sleeve ll is closed by a suitable screen QS.

The outer end of the motor shaft is extended outwardly beyond the motorV frame "and there carries a second fan 50 which rotates within the space defined by the sleeve l'l. When the sleeve lll' is in its innermost position as shown in Fig. l, the inner end of the sleeve is in substantially air. tight engagement with the plate I9 and the sleeve denes a chamber substantially closed. at .its inner end and open at its outerfend at which the screen 49 is located. Under such conditions, with the motor running, the fan 56- simply causes the rotation ofthe fan 5i! may draw air inwardly; through the screen i9 and cause such'air to pass from the inn'er'end of the sleeve 4l through a "series of holes or slots55 in the partition i9,

into the space ,'betweenthe walls ll and 35, and thence through this space to the outlet conduit 39, substantiallyin the `direction indicated diagrammatically by thearrows 66 in Fig. 2. This circulation of cool air Vdrawn in from the outside by the'fan 5@ and circulated in the space 36 will rapidly :ool the contents of the sterilizing chamber lll, the heat from which is transmitted through and radiated from the walls I! and is 'picked up bythe cool air ,flowing through the space. A i

It will now be apparent that the heating or sterilizing operation is performed with the sleeve 47 in its innermost position as shown in Fig. 1.

'f In thisA position, Vthere isf-no circulation of air through the space 36, but'the motor 25Ais running and the heating elementsl are in operation, with the .result that the air vwithin the sterilizing chamberI Mis very rapidly heated to a high degree and thev hot fair reaches all parts of the sterilizing chamber, "due-to the circulationproduced by the vfan V26.` `lll/'hen the high temperature has beenmaintained within the chamber I4 forv the required time ,to produce the desired sterilization, the sleeve lill' is pulled. out and the heating elements 3l are turned off, butthe motor 25is allowed to remain running. Thus the fan 26 continues in'v operation and continues to circulate the air Within the sterilizing chamber (no longer being heated by the heating elements) and the heat within this chamber is rapidly carried to thev metal walls H,vfrom which itis radiated or through'which it is conducted to the cool air owing through space under the influence of the vfan 50. In this way the sterilizing chamber is rapidly cooled after sterilization, but while the sterilizingchamber still remains entirely sealedv and without the ingress of any air from the outside, which might cntaminate the articles just sterilized. y Y, i i I In order to prevent Aany lpossibilityof accidentally keepingthe heating. elements in operation when'the sleeve l'l'ispulled out for a cooling operation', it vis desirable to provide i means for controlling lthefheating elements bythe position, of the sleeve ,4.7.1 yThis meanslis best shown in Figs. 3'and 4', and cliomp'rises a pair of switch contact members `iljandiZnand acarrrS` on the heating element 3l passes through the contact members 6I and 62 and is closed only when these two members are in contact with each other. When the sleeve 41 is moved inwardly to the sterilizing position shown in Figs. 1 and V3, the sleeve operates upon the cam 63 to close the contacts and thus place the heating elements 3l in operation. When the sleeve lll is pulled outwardly to the cooling position shown in Figs.2 and 4, then it releases the cam 63 and the contacts 6I and 62 spring open to disconnect the heating elements automatically.

Preferably a thermostat control is provided for all or a part of the heating elements so that I these heatingelements will automatically maintain the desired temperature in the sterilizing chamber: A thermostatic control switch of any conventional type is indicated diagrammatically at 65 and is, settable to different temperatures by means of an accessible setting knob t5. The heat responsive part of the thermostat is indicated at 6l in Figs. 1 and 2 and is preferably located behind the fan .26, as this is the coolest part of the sterilizing chamber and thus the thermostat will be responsive to ,the minimum 4temperature in the chamber rather than to the maximum temperature, which condition ishighly desirable in sterilizing apparatus. v

Preferably also the thermostatic control does not shut allA of the heating elements 3l on and off, but controls only a part of them. As Vshown diagrammatically in Fig. 5, the thermostatio switch 65 controls only the portion 3m of the heating elements, shunting this portion out oi?` operation when the predetermined temperature is exceeded, and causing continued operation of this portion 3 la when the temperature falls belowV the predetermined temperature at which the thermostatic switch has been set. The portion 3l of theheating element lwhich is not controlled by the thermostatic switch is so designed as to have sufci'ent capacity to'maintain the sterilizing chamber at approximately a steady or even sterilizing temperature when once rthe chamber has been brought up to this temperature. Thus when the sterilizing operation is commenced, all of the heating elements will be in operation to bring the chamber up rapidly to the desired temperature, but when once this temperature has been attained, the portion 34a of the heating elements which'is controlled by the thermostatic switch will be put out of operation automatically, and the unaffected portion El of the heating elements will substantially maintain the desired temperature, perhaps allowing it to drop slightly, with the result that the thermostatic switch will have toV operate only occasionally to bring the portion Sla into play briefly to maintain ther desired temperature during the sterilizing period.

A time switch indicated diagrammaticallyv at 'l0 is preferably also provided, so that the entire apparatus will be shut off at the end of apredeterrnined time even if. the operator should forget it. This time switch may be of any conventional construction and is designed Ato turn off the electricalcircuit at the end of such period after it is turned on, as will be suiiicient to bring the sterilizing chamber up to sterilizing tempera- Then, after the time switch has operated, the operator may pull out the sleeve 4l to 'the cooling position shown in Figs. 2 and 4, and may again turn on they time switch to start the cooling op'-^ elapsedpthereis, of course, nothing to prevent theoperator from opening the cover I3 and removing the sterilized articles.

Inasmuch as the temperature lvariations to which the walls I I are subjected are substantially greater than those to which the walls 35 and 31 are subjected, it follows that the expansion and contraction of the walls II will be greaterlthan that of the walls 35 and 31. Consequently, the Walls II are preferably not rigidly connected to the walls 35 and 31, but a space 15 (Figs. 1v and 2) may be left between the walls 35 and' 31 and the walls II at the top of the apparatus to allow for the difference in expansion or contraction, and also to prevent direct conduction of heat from the walls II to the walls 35 and 31. The upper edges of the walls II may be bent outwardly to form horizontal flangesl resting on blocks or strips 16 of thermal insulation.

-It=will now be seen that with the improved sterilizer of the present invention, the sterilizing chamber is completely sealed at all times when in use, both during the sterilizing operation andy lis-a feature of great importance, since any ingress of air Vfor purposes of cooling would be likely tocause'contamination of the sterilized articles.

While the sterilizing chamber I4 would be merely lled with air in the simplest form of apparatus, yet it is within the scope of the present invention to perform the sterilizingfoperation in an atmosphere of gas other than air. For example, if it is desired for any reason, a conduit may be connected to the sterilizing chamber to fill it with carbon dioxide, nitrogen, or other inert gas after the articles have been placed in the chamber and the cover has been closed, and the term gas as used in this specification 40 and in the accompanying claims is intended Y sterilizing chamber and the motor assists in reducing transmission of. heat from the sterilizing chamber to the motor and thus helps to keep the motor cool at all times.

While one embodiment of the invention has been disclosed, it is to be understood that the inventive idea may be carried out in a number of Ways. This application is, therefore, not to be limited to the precise details described, but is intended to cover all Variations and modifications thereof falling within the spirit of the invention or the scope of the appended claims.

I claim:

1. A sterilizer comprising walls and a movable closure forming a sterilizing chamber sealed against ingress of air when said closure is closed, means for heating and circulating gas within said chamber to sterilize articles therein, and means for circulating gas around said chamber in external contact with certain walls thereof to cool the interior of said chamber.

2. A sterilizer comprising walls and a movable closure forming a sterilizing chamber sealed against ingress of air when said closure is closed, one of said walls having relatively high heat conductivity, electrical heating means within said chamber, and means for circulating gas around said chamber in external contact with ysaid wall of.- relatively high heatconductivity, to cool the interior of said chamber. f

3. A sterilizer comprising walls and a movable closure forming a sterilizing chamber sealed against ingress of air when said closure is lclosed, one of said walls having relatively high heat conductivity, electrical heating means within said chamber, means for circulating heated gas within said chamber, and means for circulating gas around said chamber in external contact with said wall of relatively high heat conductivity, to cool the interior of said chamber.

'4. Al sterilizer comprising walls and a. movable closure forming a sterilizing chamber sealed against ingress of air when said closure is closet, electric heating means within said chamber, fan means also withinl said chamber, means forming a duct separated in a substantially gas tight mar-.-

ner from and in heat-exchanging relation to said chamber, and fan means for circulating gas through said duct to cool said chamber.

5. A sterilizer comprising walls and a movable closure forming a sterilizing chamber sealed against ingress of air when said closure is closed, c

thereof, means tending to circulate gas through said duct to cool said chamber, movable means for controlling flow of gas through said duct, and means operated by said movable means for controlling said electric heating means.

6. A sterilizer comprising walls and a movable closure forming a sterilizing chamber sealed against ingress of air when said closure is closed, electric heating means Within said chamber, ian means also within said chamber, motor means outside of said chamber for driving said fan means, heat insulating means between said chamber and said motor means, means forming a duct around said chamber in heat-exchanging relation with a substantial part of the walls thereof, and other fan means also driven by said motor means to tend to circulate gas through said duct to cool said chamber.

'7. A sterilizer comprising means forming a sterilizing chamber, means forming a cooling chamber in external contact with said sterilizing chamber throughout a substantial area, means for heating the interior of said sterilizing chamber, and means for circulating cooling iiuid through said cooling chamber to cool the interior of said sterilizing chamber.

8. A sterilizer comprising means forming a sterilizing chamber, means forming a fluid passageway having a portion thereof in contact with a wall of said sterilizing chamber throughout a substantial area, heating means within said ster ilizing chamber, a motor within said passageway, a fan within said sterilizing chamber driven by said motor, and a second fan in said passageway driven also by said motor to cause flow of fluid to said motor for cooling said motor and to tend to cause ow of fluid through said passageway to cool said sterilizing chamber.

9. A sterilizer comprising means forming a sterilizing chamber, means forming a fluid passageway having a portion thereof in Contact with a wall of said sterilizing chamber throughout a substantial area, heating means Within said sterilizing chamber, a motor within said passageway, a fan within said sterilizing chamber driven by said motor, a movable sleeve surrounding said motor and eiective when in one position to close said passageway at a point beyond said motor, and a second fan in said sleeve driven also by said motor to direct fluid against said motor to cool said motor when said sleeve is in closed position and to cause flow of fluid past said motor and on through said passageway when said sleeve is in open position, to cool said motor and also to cool said sterilizing chamber.

l0. A sterilizer comprising means forming a sterilizing chamber, means forming a uid passageway having a portion thereof in contact with a wall of said sterilizing chamber throughout a substantial area, heating means Within said sterilizing chamber, a motor within said passageway, a fan within said sterilizing chamber driven by said motor, a movable sleeve surrounding said motor and eiective when in one position to close said passageway at a point beyond said motor,

a second fan in said sleeve driven also by said mov tor to direct fluid against said motor to col said motor when said sleeve is in closed position and to cause flow of fluid past said motor and on through said passageway when said sleeve is in open position, to cool said motor and also to cool said sterilizing chamber, and means controlled by movement of said sleeve from closed position to open position for rendering said heating means inefective.

11. A sterilizer comprising means forming a sterilizing chamber substantially completely sealed from access of external air during both heating and cooling operations, means for heating the interiorof said chamber to sterilize articlesr therein, means for coolingthe interior f said` chamber without disturbing the sealed condition thereof, to cool sterilized articles without contaminating them, said cooling means including a cool fluid duct in heat exchanging relationship to said chamber, valve means for controlling ow of fluid through said duct, means for automatically rendering said heating means inoperative upon opening said valve means, and means for agitating the gas within said chamber both during operation of saidk heating means and during operation of said cooling means, to promote rapid heating or cooling, respectively, of all of the gas within said chamber.

12. A sterilizer comprising means forming a sterilizing chamber substantially completely sealed from access of external air during both heating and cooling operations, means for heating the interior of said chamber, means forming a gas duct in heat exchanging relationship to said chamber, `means for circulating cool gas through said duct to cool the interior of said chamber, and means for agitating the gas within said chamber during the circulation of the cool gas through said duct, to promote the rapid coola ing of all of the gas within said chamber.

13. A sterilizer according to claim 12, in which said means for circulating cool gas through said duct is a fan located externally of said sterilizlng chamber, and in which said means for agitating gas within vsaid chambervis another fan located within the chamber, further including a single motor for driving both of said fans.

CHARLES R. MEITZLER. 

